Most types of mowers, such as lawn mowers and brush mowers, include a deck with a downwardly extending skirt. Typically, the skirt is of uniform width and forms a cutting chamber surrounding the mower blade. The skirt generally includes a discharge opening for discharging cut vegetation.
Unlike conventional lawn mowers, however, brush mowers require a wide intake opening at the front end of the deck so that large brush (e.g., saplings) and other dense vegetation (including tall grass) can be readily received into the cutting chamber. This allows for the mower blade to efficiently cut the vegetation, which is often significantly taller than the height of the opening at the front end of the mower deck.
When brush mowers are used to cut grass and other leafy vegetation in a field or lawn, two disadvantages of the open front cutting deck become apparent. First, because the circular airflow created by the blade's circular motion is diverted as it encounters the open front, uncut grass ahead of the mower tends to be blown downward reducing the cleanness of the cut. Second, a significant portion of the cut vegetation is often ejected from the cutting chamber via the intake opening rather out the discharge opening. This is undesirable because forwardly discharged cut vegetation can build up in front of the mower, increasing the volume of material to be cut, thereby requiring the motor to work harder.
To date, solving the problem of forward discharge of cut vegetation from a brush mower has presented a dilemma. If the skirt of the deck is extended to block the front end in the manner typical for conventional lawn mowers, forward discharge of vegetation will be restricted. Unfortunately, a key feature of the brush mower, the ability to cut tall grass and woody vegetation, will be severely compromised with such approach.
Another possible solution is to reduce the height of the skirt across the front of the cutting deck relative to the skirt height on the remainder of the deck so as to achieve a partial intake opening at the front of the deck. For example, U.S. Pat. No. 4,633,658 ("the '658 patent") discloses a lawn mower with a downwardly extending skirt which is shorter in height in the front end than in the back end. A discharge opening is provided in the back end of the deck. This mower is designed to be attached to a conventional portable weeder. While the skirt at the front may act to prevent forward discharge of grass from the mower, the intake opening is not believed to be of sufficient size to permit tall and woody vegetation to be cut quickly and easily, if at all. Indeed, while the height of the skirt is less in front than in the rear, it appears the deck was designed this way to allow the operator some latitude in tilting the mower back and forth about the set of wheels, in a manner common to portable weeders.
Thus, the motivation for the reduced-height skirt at the front of the deck of the '658 patent is different than the motivation for an open front end on the deck of a brush mower. Moreover, use of a deck of the type described in the '658 patent on a brush mower would significantly reduce the size of the intake opening, which in turn would critically impact the ability of the brush mower to cut tall vegetation.
Thus, there is a need for a deck design that will substantially reduce the amount of cut vegetation that is forwardly discharged in brush mowers, while at the same time not significantly reducing the size of the open front end of the mower.